1. Field of the Invention
The present invention relates to a silicon carbide crystal ingot, a silicon carbide crystal wafer, and a method for fabricating a silicon carbide crystal ingot.
2. Description of the Background Art
In recent years, the usage of silicon carbide (SiC) single crystal for a semiconductor substrate employed in fabricating a semiconductor device is in progress. SiC is known to have a band gap greater than that of silicon (Si) that has been used more commonly. Therefore, a semiconductor device employing SiC is drawing attention by having advantages such as high breakdown voltage, low ON resistance, and less degradation in properties under high-temperature environment.
For example, PTL 1 (U.S. Pat. No. 3,876,628) discloses the method of growing a SiC single crystal ingot through sublimation upon introducing n-type dopant atoms having an atomic radius smaller than that of silicon together with heavy metal atoms such as titanium, vanadium, or tantalum having an atomic radius larger than that of silicon into a SiC single crystal ingot.
According to the method of PTL 1, the strain in the SiC single crystal ingot can be alleviated by canceling the compression strain generated in the SiC single crystal ingot caused by introducing n-type dopant atoms having an atomic radius smaller than that of silicon by the introduction of heavy metal atoms having an atomic radius larger than that of silicon (for example, refer to Paragraphs [0038]-[0046] PTL 1).